BB just sits there, travel down barrel.

Having an issue with an M4 i put away a couple years ago. the round will not leave the receiver. if you hand feed one bb, turn it upside down and pull the trigger, you see the bb just dance around. i feel air leaving the end of the barrel.
what are some things i should be looking into?

Having an issue with an M4 i put away a couple years ago. the round will not leave the receiver. if you hand feed one bb, turn it upside down and pull the trigger, you see the bb just dance around. i feel air leaving the end of the barrel.
what are some things i should be looking into?

What model M4 is it? Open the upper receive and dry fire the gun to see if the nozzle is cycling. If it is not then there is most likely an issue with the tappet plate. Was the modded or disassembled prior to storage? It could be as simple as the nozzle not be fitted in the tappet plate. Or is could be a broken tappet, or it could be some other issue but lets start there.

Wiring. Your wiring may be crowding the BB-Ramp area and blocking the Air Nozzle. Make sure the wiring is out of the way when closing the upper receiver. Also make sure the wiring is out if the way as it is tucked in the upper corner of your mag-well. It may have sunk down a bit not allowing the Mag to line up correctly with the BB-ramp, though it is technically locking in place at the mag-catch.

Wiring. Your wiring may be crowding the BB-Ramp area and blocking the Air Nozzle. Make sure the wiring is out of the way when closing the upper receiver. Also make sure the wiring is out if the way as it is tucked in the upper corner of your mag-well. It may have sunk down a bit not allowing the Mag to line up correctly with the BB-ramp, though it is technically locking in place at the mag-catch.

What model M4 is it? Open the upper receive and dry fire the gun to see if the nozzle is cycling. If it is not then there is most likely an issue with the tappet plate. Was the modded or disassembled prior to storage? It could be as simple as the nozzle not be fitted in the tappet plate. Or is could be a broken tappet, or it could be some other issue but lets start there.

Its the CQB. there is air coming from the end of the barrel, its just not accompanied by a BB. I pulled the gearbox out and found the SLIGHTES leak around where the brass meets the plastic on the cylinder head.

Its the CQB. there is air coming from the end of the barrel, its just not accompanied by a BB. I pulled the gearbox out and found the SLIGHTES leak around where the brass meets the plastic on the cylinder head.

The first thing I would look at external of the gearbox is the feed ramp to see if that's damaged or not aligned properly. Misalignment can occur when the ramp is not tightened properly or the wire harness is pushing on it.